Referring to FIG. 1, it is illustrated that a prior art ruler 92 of a measure tape is made as a long metal thin piece, for example, a steel strip by cold rolling. A distal end of the ruler is riveted with an L shape ruler hook 91 for hooking a measured bench mark of an object to be measured. To enhance the stability of the ruler hook 92, a pad 93 is added at a bottom of the ruler.
In measuring, in general, the ruler hook is hung upon the measured bench mark of an object having a right angle on the shape of the object. When the object to be measured has an inclined slope, a cambered section, or a spherical surface, such as a round tube, a round edge, a round corner, a ball, etc., the ruler hook 91 is easily to slide out. When the ruler vibrates, the ruler hook very possibly slides out so that the measurement is stopped. When the measured bench mark is at a smooth surface, the ruler hook is easy to slide thereon so that the measurement is difficult. Therefore, to improve this problem, as shown in the FIG. 2, a distal end of the ruler hook is added with a small hook 94 or a positioning nail 95 is used to fix the ruler hook.
However, above way is used in finite cases. For example, the ruler hook 91 with a small hook 94 is only used to a recessed measured bench mark. The positioning nail 95 is only used for a wood material. Moreover, the above mentioned ways are only used in some special cases, but most of the conditions are not suitable by the prior art ways.